Gauge adaptor for automatic shotguns



E. P. SIMMONS March 25, 1958 GAUGE ADAPTOR FOR AUTOMATICSHOTGUNS 2 Sheets-Sheet 1 Filed Jane 11, 1956 E. P. SIMMONS GAUGE ADAPTOR FOR AUTOMATIC SHOTGUNS' March 25, 1958 Filed June 11, 1956 2 Sheets-Sheet 2 United States Patent 2,827,728 GAUGE ADAPTOR FOR AUTOMATIC SHOTGUNS Ernest P. Simmons, Kansas City, Kane. Application June 11, 1956, Serial No. 590,717 6 Claims. (Cl. 42-17) This invention relates to new and useful improvements in shotguns, and relates particularly to shotguns of the automatic or self-loading type.

The principal object of the present invention is the provision of means whereby an automatic shotgun of a given gauge may be adapted to fire ammunition of a smaller gauge. It is well known that a shotgun may be chambered to receive smaller shells than those for which the gun was originally designed, and that said smaller shells may safely be fired through the larger barrel. However, such smaller shells cannot, in any gun within my knowledge, be handled properly by the automatic reloading mechanism of the gun, thereby necessitating that such a rechambered gun be fired on a singleshot basis. This invention is concerned primarily with modifications to the reloading mechanism whereby it is adapted to handle shells of the smaller gauge.

Another object of the present invention is the provision of adapting means of the character described which may selectively be rendered efiective or non-effective, so that the gunner may easily and quickly adapt the gun for using either the smaller or the larger ammunition.

Other objects are simplicity and economy of structure, efiiciency and dependability of operation, and ready applicability of the adaptation to pre-existiug guns.

With these objects in view, as well as other objects which will appear in the course of the specification, reference will be had to the drawing, wherein:

Fig. l is a longitudinal vertical sectional view of the receiver and adjacent portions of an automatic shotgun having gauge adaptors embodying the present invention applied thereto, with portions left in elevation and portions broken away, with all parts shown adapted to receive shells of the smaller gauge,

Fig. 2 is a fragmentary view similar to Fig. 1, showing the parts adapted to receive shells of the larger gauge,

Fig. 3 is a sectional Fig. 1,

Fig. 4 is an enlarged, detached perspective view of the spring retainer clip for the magazine follower,

Fig. 5 is a fragmentary view similar to Fig. 1, showing the position of the parts immediately after the firing of the gun, with the bolt retracted and a new shell positioned on the carrier, and with the carrier lock left in elevation,

Fig. 6 is a sectional view taken on line VI-VI of Fig. 5,

Fig. 7 is a fragmentary view similar to Fig. 6, showing the position of the carrier lock when no shell is disposed on the carrier,

Fig. 8 is a fragmentary view similar to Fig. 6 showing the gun adapted to receive shells of the larger gauge, and with a shell positioned on the carrier,

P Fig. 9 is a sectional viewtaken on line IXIX of Fig. 10 is a fragmentary sectional view taken on line X-X of Fig. 1, and

.-Fig. 11 is an enlarged, detached perspective view of the adaptor providing for operation of the carrier lock by shells of the smaller gauge.

view taken on line III-III of Like reference numerals apply to similar parts throughout the several views, and the numeral 2 applies to the receiver portion of an automatic shotgun of the splitchamber type, said receiver being elongated longitudinally of the gun and having right and left side walls 4 and 6, top wall 8, and being open at the bottom. The rearward portion of the bottom opening is closed by a trigger frame 19 secured in the receiver by an assembly pin 12, and the forward portion of said bottom opening forms a carrier opening through which the magazine may be loaded, as will be described.

The gun barrel 14'is threaded into the forward end of the receiver, and communicates therewith. A magazine tube 16 is disposed beneath and parallel to the barrel, and is also threaded at its rearward end into the receiver in communicating relationship therewith. A magazine spring 18 disposed in the magazine is operable to urge shells disposed in said tube rearwardly into the receiver, said spring abutting at its forward end against a magazine tube plug (not shown) and at its rearward end against a follower slidable in the tube.

The first adaptation of the gun permitting the use of ammunition of two different gauges is a special follower. As shown, said follower comprises a sleeve 20 slidable axially in the magazine, said magazine tube having a diameter sufficient to admit a shell 22 of the larger gauge, and said sleeve having an internal diameter at its forward end too small to admit shell 22, but large enough to admit a shell 24 of the smaller gauge. Also carried slidably in the magazine tube is a forwardly opening cup 26 having a rearward extension 28 of a diameter adapted to enter and extend rearwardly through sleeve 20. Spring 18 is seated in said cup. A C-shaped spring clip 30, shown separately in Fig. 4, is adapted to be snapped externally about the magazine tube 16 just forwardly of the receiver. Said clip includes an integral segmental insert 32, which projects inwardly through a slot 34 formed in the magazine tube adjacent the forward edge of sleeve 20, thereby serving as a stop preventing forward movement of said sleeve. Said clip is placed in position when it is desired to use shells 24 of the smaller gauge as shown in Figs. 1 and 3, the shell passing slidably through sleeve 20. When it is desired to use shells 24 of the larger gauge, as shown in Fig. 2, clip 30 is removed, and the shells push both the sleeve and the cup forwardly as shown. In either case, it will be seen that the effective diameter of the rearward portion of the magazine tube is adjusted so that excessive lateral wobbling of the shell, either horizontally or vertically, is prevented as the shell is urged rearwardly into the receiver. It will be seen that cup 26 is provided with an external rearwardly facing shoulder 36 which engages an internal forwardly facing shoulder 38 of sleeve 20 to insure that the sleeve will be urged rearwardly with the cup, and that the sleeve is provided with an external rearwardly facing shoulder 40 (Fig. 2) which engages a forwardly facing internal shoulder 42 of the magazine tube, whereby rearward movement of the sleeve is limited. Access for insertion or removal of clip 30 can be had only when the forepiece 44 of the gun is removed.

Carried for longitudinal sliding movement in the rearward end portion of barrel 14 is a tubular shell chamber 46 adapted to receive a shell 24 of the smaller gauge as shown in Fig. 1. As best shown in Figs. 1 and 5, said chamber is provided at its rearward end with an internal shoulder against which the rearward end of the barrel. While as shown the bore 50 of the chamber is sized to receive a shell 24 of the smaller gauge, it would obviously be necessary only to substitute a chamber having rim of the shell'seats, and an external shoulder 48 which normally abuts the a larger bore to receive a.

asamas shell not the larger gauge. This larger bore is indicated'in dotted'l'ines at 50" in Fig. l. The chamber is provided with a rearward extension 52 having the form generally of a downwardly opening semi-cylinder co-axi-al with the chamber. The'reaiward end of said extension terminates in spaced relationfrom-aforwardly facing shoulder 54 formed internally in receiver 2. As-best shown in Fig. 1, chamber shoulder 48 'isurged forwardly to engage the rearward end of the barrel by a pin 56 carried in the wall of extension 52 and urged rearwardly against shoulder 54 by spring 58.

The bolt 60,.when the gun is closed, is disposed within chamber extension 52, the forward end thereof abutting.

the rearward end of the shell 24 in chamber 46, as shown in Fig. 1. Adjacent its rearward end, said bolt is provided with an upwardly projecting lug 62 which extends into slot 64 formed in chamber extension 52, whereby to lock the bolt against rearward movement relative to said extension. The bolt carries a firing pin mechanism per se is not pertinent to the present invention, it will be understood that when trigger 68 is pulled, a hammer 70 carried by trigger frame 10. and shown in its cocked position in Fig. 1 will be pivoted forwardly and upwardly to strike the rearward end of the firing pin, which will then be projected forwardly from the bolt to detonate shell 24 in a manner wellknown in the art. Said-bolt also. carries an extractor 72 which functionsin theusual manner to engage the rim of the shell-in the chamber, and to draw'itfrom thechamber when thebolt moves rearwardly as the gun opens.

The bolt is supported in pin 74 extending transversely of the gun, passingvthrough a pair of matching slots 76 formed in a pair-ofside-walls 78 and. 80 which are integral with and depend. from the bolt- The forward end portions of said slots in which pin 74- is disposed when the bolt is closed, are substantially horizontal. The rearward portions of said slots are-inclinedupwardly and rearwardly, as best shown in Fig. 1, for apurpose which will appear. Pin 74 extends outwardly from the sides of the bolt, and is supported respectively inright and left slides82 and 84 (see- Fig. 9). Said slides are mounted respectively for forward and rearward sliding movementin grooves 86 and 88 which are formedrespectively in the inner surfaces of receiver walls 4 and 6. The right slide 82 is provided with athumb-piece 90 which projects outwardly through an ejection opening 92, formed in-receiver wall 4, whereby the slide may. be operated manually.

A.link-94 is pivoted .at its forward end onpin 74-between-the bolt side walls 78 and 80, and extends rearwardly through-the receiver. At-its rearward end, it is pivoted as at. 96 to-an:inertia rod 98 which is carried for longitudinal sliding movement in a'tubular extension100 of the receiver, said extension being disposed in the stock 102. Saidinertia rod'is urged forwardly by a closing spring, not shownpcarried in extension tube 100 behind said rod.

A shell carrier 104 having the upper surface thereofcylindrically curved is disposed in the lowerforward portion of the receiver, substantially in alignment with magazine tube 16, so as to receive thereon each -shellasit-is ejected from the mngazine by spring. 18. his provided atitsrearward end with an upstanding wall 106 which. servesto arrest the rearward movement-.ofa shell thereon. Said carrier is supported by a rearwardly extending integral arm 108 whichextends along the right side-of trigger frame 10, and which is mounted on a horimntal transverse pin 110 which is pivoted in frame 10. Saidaarm extends-rearwardly -from pin 110, and. a pawl 112 isrpivoted to-the rearwardiend thereof.at-.114. A SPIiIIQflll serves both. to urge pawl 112 upwardly and;forwardly .to the positionrshownin. Fig.1. l,..andito.urge downward movement of carrier 104-downwardly: The the' earrier' is limitedbya. pair ofinwardly. projecting lugs 118 formed-respectively'on. receiver walls 4and 6 and projecting=.inwardly-therefrom (see Figs. 7 and 9). As best 66. Although the firing.

the receiver by a horizontalform of a flat bar with the shown in Figs. 1 and 2, the rearmost shell in the magazine is prevented'from moving rearwardly onto the carrier when the bolt is closed by the engagement of the base of said shell between the bevelled forward end of the carrier and a depending bevelled tang 122 which is integral with the bolt. In order to accommodate the gun to receive ammunition of two different gauges, it is necessary to bend the forward end portion of the carrier upwardly as shown, in orderthatthe smaller shells will be caught between the carrier and tang 122. However, one carrier will be adequate for both sizes, the difference of diameter of the shell basesbeing reflected merely in the fact that said bases will engage different sections of the bevelled faces of the carrier and tang. Another modification of the carrier is that the upper surface thereof, just forwardly of rear wall 106, is provided with an elevating ramp 124 which slopes upwardly to the rear, for a purpose to be described.

A carrier lock 126comprises a substantially flat bar disposed parallel to and just above the normal lowered position of carrier 106, and which is disposed in a groove 128 formed in the inner surface of receiver side wall 4. It is pivoted on a vertical pin 130 threaded in said side wall, said. pivot pin being disposed intermediate the ends ofthe lock bar. Said lockbar is pivotally movable from a position lying substantially entirely within groove 128,

whichwill be termed its inoperative position, to a positionwherein the rearward end portion thereof projects inwardly with the receiver which will be termed its operative position. In the operative position, the rearward end of the lockbar overlapsan upwardly facing shoulder 132 formed on carrier. arm 108, and rests against a stop 134 which-rises from saidshoulder, and thus locks the carrier against elevation. The lock bar is urged toward its opera-- tive positionby a compression spring 136 disposed between thelock bar and receiver wall 4 (see Figs. 5-8). The carrier lock may be moved manually to its inoperative position by means of a push button 138 fixed thereto and projecting outwardly through a hole 140 provided therefor in.

receiver wall 4. The carrier lock bar is provided at its forward end with an inwardly turned tooth 142. Said tooth serves to prevent shells from being ejected rearward- 1y from the magazine when the carrier is elevated, as will be described.

The general operation of the gun is as follows: Assumingfirst that the gun is in position for firing as in Fig. l, trigger 68 is pulled, releasing hammer 70 which then strikes firing pin 66 which detonates shell 24 as previously described and as-well known shock of the explosion drives bolt 60, chamber 46 and chamber extension 52 rearwardly as a unit, since the bolt is locked in the' extension by lug 62. This initial movement is also transmitted through pin 74 and link 94 to inertia rod 98. The movement of the chamber and extension thereof is arrested by engagement with receiver shoulder 54, but the rearward movement of pin 74, link 94 and inertia rod-continues, due to the momentum applied thereto during the chamber movement. After a very slight delay, duringwhich pin 74 traverses the horizontal. portiuns of bolt: slots 76, said pin enters the inclinedportions. of said slots, thereby-camming the rearward end-of: the'boltdownwardly and extracting locking lug .62.out of'.charnber extension slot64. With the-bolt thus un1ocked,.it-is forced. rearwardly by the residual pressure of the gases of explosion in the barrel, and also by-sthe: momentum of in'ertia-rod 98 and link 94.

As-theboltmoves-rearwardly, extractor 72 pulls shell 24 out of the chamber, an'das the bolt'reaches'the'rear ward limit of; its travel, as shown in Fig. 5, an ejector, not shown, engages said shell and flips it to the right through:ejectiont opening 92. Also, as thebolt moves rearwardly and hence moves tang 122 out of the path oft-the:rearmostshellin the magazine, said shell will be 18, until it is stopped in the art. The first recoil.

As said shell moves rearwardly, the rim thereof moves along the inner surface of carrier lock bar 126, forcing said bar outwardly to its inoperative position within receiver groove 128. It is of course necessary that the lock be inoperative when the carrier is to be pivoted upwardly to move the shell carried thereby into the path of the bolt, as will be described.

As will be seen in Fig. 8, the transverse spacing be tween receiver walls 4 and 6 is such that the base or rim of the larger shells 22 fit rather closely therebetween, and that said shell rim has ample diameter to force carrier lock 126 to its inoperative position. However, the rim of the smaller shell 24 does not have suflicient diameter to force the carrier to its inoperative position, and an adaptor is therefore necessary. As shown in Figs. 1 and 5-7, said adaptor comprises a plug 144 inserted in a bore 146 provided therefor in receiver wall 6 directly opposite the rearward end portion of the carrier lock bar, and just above the rearward end portion of the carrier. Said plug is secured releasably in place by a pair of screws 148 threaded in wall 6, the heads of said screws overlapping the outer end of said plug. Said plug extends into the receiver, the inner end thereof being bevelled to form a cam surface 150 which slopes inwardly and rearwardly from the inner surface of wall 6. The transverse throw of said cam is such, as clearly shown in Fig. 6, that a smaller shell 24 will be forced to the right thereby sufficiently that said shell will move carrier lock 126 to its inoperative position. When it is desired to use shells 22 of the larger size, plug 144 is replaced by a dummy plug 152 as shown in Fig. 8, the inner end of said dummy plug being substantially flush with the inner surface of wall 6. It will be seen that the left edge of carrier 126 is notched at 154 to permit said carrier to move upwardly past the projecting cam portion of plug 144. Also, the upper portion of cam 150 may be cut away as indicated at 156 in order not to interfere with the downward motion of bolt 60 as said bolt is unlocked.

During the final portion of the rearward movement of bolt 60, the rearward edge of the right side wall 80 of the bolt contacts carrier pawl 112 and pivots said pawl rearwardly and downwardly, against the pressure of spring 116. The lower edge of said side wall then rides over the pawl until the toe 158 of said pawl snaps upwardly into engagement with a notch 160 formed in the lower edge of said side wall. The parts then have the position shown in Fig. 5, the bolt being urged forwardly against pawl 112 by the closing spring. Since the line of force of the bolt on the pawl, which extends from notch 160 through pawl pivot 114, passes below carrier pivot 110, the first forward movement of the bolt causes the pawl and the rearward portion of carrier arm 108 to act as a toggle, buckling the pivot 114 downwardly and forcing carrier 104 upwardly thereby moving the shell disposed on the carrier upwardly into chamber extension 52, in the path of the bolt. The ramp 124 at the rearward end of the carrier elevates the rearward end of the shell, as shown in Fig. 5, to insure that a shell 24 of the smaller size will be lifted sufiiciently high to be engaged and pushed forwardly by the bolt. The presence of the ramp does not prevent proper handling of the larger shells. While carrier 104 is elevated, any shells present in the magazine are prevented from being ejected by carrier lock tooth 142, which is then extended behind the magazine as shown in Figs. 6 and 8.

As the bolt moves forwardly, it is disengaged from pawl 112, thereby permitting return of the carrier to its lowered position. The bolt then continues its forward movement to push the shell into the chamber to ready the gun for the next shot, the bolt lug 62 being cammed upwardly into chamber extension slot 64 by pin 74, and the hammer 70 having been cocked by link 94 during the rearward stroke of the bolt.

It will of course be apparent that if the magazine is empty and hence deposits no shell on the carrier, the

carrier lock will, after the last shot, remain operative as shown in Fig. 7, and the gun will remain locked in the open position shown in Fig. 5. The gun may then be reloaded through ejection opening 92, and the gun closed by manually depressing push button 138 to release the carrier lock. With the gun closed, reloading may be accomplished through the bottom opening after first depressing button 138 to permit carrier 104 to be pressed upwardly.

Thus it will be seen that I have produced a simple and effective adapting means whereby a larger gauge gun, say ZO-gauge, may be adapted to handle smaller gauge ammunition, say 28-gauge. The adaptation for smaller gauge ammunition is a three step operation involving the insertion of a chamber 46 bored for the smaller ammunition, the insertion bf magazine spring clip 30, and the insertion of adaptor plug 144 in place of dummy plug 152. The gun may be readapted for the larger ammunition by simply reversing these three steps.

While I have shown and described a specific embodiment of my invention, it will be apparent that many minor changes of structure and operation could be made without departing from the spirit of the invention as defined by the scope of the appended claims.

What I claim as new and desire to protect by Letters Patent is:

1. The combination, with an automatic shotgun having a receiver with opposite side walls, a shell carrier disposed between said side walls and adapted to receive thereon a shell ejected horizontally from the magazine of the gun, a bolt, means operable by said bolt to elevate said carrier as said bolt moves into battery to lift said shell into the path of said bolt, and a carrier lock carried in one of said side walls and normally projecting horizontally over said carrier to prevent the elevation of said carrier, said carrier lock being movable horizontally to an inoperative position outward from said carrier by a shell as it enters on said carrier, said shell normally being prevented from moving laterally of the receiver by its sliding engagement with the side wall of said receiver opposite said carrier lock, of an adaptor for permitting the use of smaller gauge shells in said gun, said adaptor comprising a member atfixed in the side wall of said receiver directly opposite said carrier lock, said member projecting inwardly into said receiver whereby to force a shell of said smaller gauge toward the side wall carrying said carrier lock, whereby to force said carrier lock to its inoperative position.

2. The structure as recited in claim 1 wherein said adaptor member comprises a cam having a bevelled surface sloping inwardly from the side wall in which the member is mounted, in the direction of travel of a shell as it enters onto said carrier.

3. The structure as recited in claim 1 wherein said adaptor member comprises a cam having a bevelled surface sloping inwardly from the side wall in which the member is mounted, in the direction of travel of a shell as it enters onto said carrier, said cam member being detachable from the receiver wall in which it is mounted, whereby the gun may be readapted for use with shells of normal gauge.

4. The structure as recited in claim 1 wherein said adapter member comprises a cam having a bevelled surface sloping inwardly from the side wall in which the member is mounted, in the directon of travel of a shell as it enters onto said carrier, said cam member being detachable from the receiver wall in which it is mounted, and interchangeable with a dummy member the operative surface of which is substantially flush with the inner surface, of said side wall, whereby the gun may be readapted for use with shells of the normal gauge.

5. In combination with an automatic: shotgun having a magazine tube adapted to receive slidably therein shells of a given larger gauge, and a spring disposed in said tube and adapted to urge said shells toward the open rearward end ofsaid tube, of a spring follower interposed between said spring and said shells, :and adapting said magazine to receive shells of a smaller gauge and to prevent undue lateral wobbling of said smaller shells as they are ejected from said tube, said follower comprising a tubular sleeve slidably mounted in said tube and having an internal diameter suflicient to receive therethrough a shell of said smaller guage but not a shell of said larger gauge, and a spring cup slidably carried in said tube forwardly of said sleeve and having a reduced rearward extension adapted to extend slidably through said sleeve, said spring seating in said cup, and stop means carried removably by said magazine tube and operable to restrain said sleeve against forward movement.

6. The structure as recited in claim 5 wherein said stop I member fixed thereto and adapted to extend inwardly through an aperture formed on said tube just forwardly of said sleeve, whereby to lock said sleeve against forward movement.

References Cited in the file of this patent UNITED STATES PATENTS 908,521 Trundle Jan. 5, 1909 1,034,122 Knous July 30, 1912 971,597 Browning Aug. 28, 1934 2,026,252 Russell et a1 Dec. 31, 1935 

